Note that I'm using Gnome (Unity) which infamously handles the layout switch itself nowadays rather than letting X do so (see e.g. https://bugs.launchpad.net/gnome-settings-daemon/+bug/1244090). I guess the contents of /etc/default/keyboard are completely overridden by Gnome.
I have XKBOPTIONS="" in that file.
Note that I'm using Gnome (Unity) which infamously handles the layout switch itself nowadays rather than letting X do so (see e.g. https:/ /bugs.launchpad .net/gnome- settings- daemon/ +bug/1244090). I guess the contents of /etc/default/ keyboard are completely overridden by Gnome.